. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. VARIATION 21 interrelated causes acting simultaneously, each being independently capable of inducing a change in the end product, may cause an iufinile number of differences in substance and in degree of development. Variation and Environment.—External stimuli affect the develoj)- ment of characters in three ways: (1) they modify the development of inherited characters; (2) they actually condition the production of charac- ters whose hereditary determiners are present in the gei'nr-plasm; (3) they
. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. VARIATION 21 interrelated causes acting simultaneously, each being independently capable of inducing a change in the end product, may cause an iufinile number of differences in substance and in degree of development. Variation and Environment.—External stimuli affect the develoj)- ment of characters in three ways: (1) they modify the development of inherited characters; (2) they actually condition the production of charac- ters whose hereditary determiners are present in the gei'nr-plasm; (3) they may cause germinal variations which result in the appearance of new heritable characters. The following are illustrations of these effects with reference to particular environmental Fig. 4.—Scdum spcc/abilc. The three shoots (taken from a, single plant) were planted in small pots on March 12, 1904, and placed in different greenhouses: /, in blue Ught; //, in mixed white light; ///, in red light. Photographed on Sept. 30, 1914, (After Klebs.) 1. Environment Modifies Development of Inherited Characters.— (a) Light mid Function.—Klebs reports the results of growing the Showy Sedum {Sedum spectabile) in white, red and blue light. The diverse effects of the three kinds of light are clearly shown in Fig. 4, Although the visible differences between the three plants were very pronounced the experiment was carried much further. During observations were made on the numbers of stamens in the fiowers of plants similarly propagated under white, red and blue light and under various conditions of temperature, moisture, and food. About 20,000 flowers were examined Digitized by Microsoft®. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Babcock, E. B. (Ernest Brown), b. 1877; Clausen, Roy Elwood,
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Keywords: ., bookcentury1900, bookdecade1910, booksu, booksubjectplantbreeding
